1. Industrial Field of Use
This invention relates to a clamping apparatus for use in lifting objects such as cases of soft drink cans or bottles. More particularly, it relates to a clamping apparatus capable of lifting an entire layer of objects by grasping the sides of the layer.
2. Description of the Related Art
Soft drink cans and bottles are commonly shipped from factories in cases or trays stacked on pallets, which can be lifted with a fork lift. Each pallet supports one or more layers of the cases or trays. Typically, a pallet as shipped from a bottling factory contains a single type of product. However, retailers of soft drinks frequently order less than an entire pallet of a particular type of soft drink. For example, a retailer may desire a half pallet of orange soda, a quarter pallet of grape soda, and a quarter pallet of ginger ale. Therefore, before soft drinks are shipped to a retailer, they may be unloaded by a distributor from pallets containing a single variety and repacked as pallets containing more than one variety of soft drinks.
The process of unloading and reloading pallets of soft drink cases is usually done by hand. This is monotonous and arduous work, and often results in physical injuries to the laborers who do this work. Furthermore, manual transfer of cases between pallets is a slow process, and a typical worker can unload and reload no more than 500 cases of soft drink cans per hour. This same problem exists with many other types of products, such as alcoholic beverages and grocery products, which are shipped from factories in lots too large for a single retailer to use and so are unloaded and reloaded by hand by a distributor to obtain pallets containing a suitable number of goods for shipment to a retailer.
Clamping devices have been developed which can lift one or more entire layers of objects (such as bricks) at a time from a pallet and move the layers to a different pallet. These devices typically have four clamping arms which pivot about horizontal axes to clamp the outer surface of a layer from four directions at once. The clamping arms, with the layer of bricks or other objects held between them, can then be transferred to a new location by a fork lift, a crane, or other lifting mechanism. However, these conventional clamping devices are all designed for lifting layers having specific fixed dimensions and are not suitable for lifting layers of variable dimensions. For example, if a clamping device designed for lifting a perfectly square layer is used to lift an elongated rectangular layer, two of the clamping arms will grasp the layer at a different height from the other two clamping arms.
With some objects, this difference in height may not be a problem. However, with cases of soft drinks, for example, a difference of a few inches between the heights where the clamping arms contact the different sides of the layer can make it impossible for the clamping arms to lift the layer. Accordingly, there is a need for a clamping apparatus which can be used to lift both square objects and elongated rectangular objects while holding all four sides of the objects at substantially the same height.
Sometimes, a layer of objects which is to be lifted contains a cavity at its center. There is also need for a clamping apparatus which can lift such a layer without damage to the objects in the layer.